1. Field of the Invention
This invention relates to a fastener composed of male and female members to be coupled together by insertion, in which the male member can be inserted into the female member longitudinally within a generally fan-shape range and can be angularly moved within a predetermined range after the insertion, and to more particularly to a belt buckle to be used for a clothing, a suspender, a bag, a sports equipment, etc.
2. Description of the Related Art
This type of buckle is currently known (Japanese Design Registration No. 794905) which comprises a socket body having a hollow and a locking hole formed in a front surface of the socket body and communicating with the hollow, and a hook-shape plug body to be inserted into the hollow and having a locking portion to be resiliently received in the locking hole and to be locked with a forward end of the locking hole and in which the plug body can be moved freely within a predetermined angle with respect to the socket body.
With the known buckle described in the previous paragraph, partly since the buckle is made of plastics, and partly since the socket body has upper and lower plates defining therebetween a hollow into which the plug body is to be inserted has in each of opposite side walls an opening communicating with the hollow portion, the plug body can be angularly moved freely within a predetermined range when it is inserted into the socket body for coupling therewith.
However, when it is in use, this conventional type buckle would not necessarily bear only a plane load; that is, a twisting or wrenching force would act on the plug body. Since the forward end of the socket body is apt to be deformed as it is coupled with the plug body at the forward side, the upper and lower plates would be forced apart from each other so that the plug body will easily be released from the socket body.
Assuming that the plug body is twisted so as to thrust the upper plate of the socket body upwardly when the socket and plug bodies cross each other at an angle, e.g. about 120.degree., the plug body will be removed from the plug body with maximum ease.